Phosphorous-halogen fog stabilizers for photographic emulsions

ABSTRACT

A PHOTOGRAPHIC SILVER HALIDE EMULSION OR PHOTOGRAPHIC ELEMENT CONTAINING A FOG-STABILIZING AMOUNT OF AN AMIDE CONTAINING BOTH PHOSPHORUS AND HALOGEN IN THE MOLECULE, THE PHOSPHORUS ATOM BEING ATTACHED TO THE AMIDIC NITROGEN ATOM.

Patented Mar. 2, 1971 3,567,587 PHOSPHOROUS-HALOGEN FOG STABILIZERS FOR PHOTOGRAPIHC EMULSHONS Donald M. Burness, Robert A. Silverman, and Charles J. Wright, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. N Drawing. Filed Mar. 3, 1967, Ser. No. 620,244 Int. Cl. G03c l/34 US. Cl. 196-109 18 Claims ABSCT OF THE DISCLOSURE A photographic silver halide emulsion or photographic element containing a fog-stabilizing amount of an amide containing both phosphorus and halogen in the molecule, the phosphorus atom being attached to the amidic nitrogen atom.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to new and improved antifoggants and stabilizers for photographic elements and to photographic silver halide emulsions containing said antifoggants and stabilizers therein.

Description of the prior art During development of a silver halide emulsion, small amounts of silver halide are reduced to metallic silver regardless of whether or not they have been exposed. This reduction of silver ion produces a background fog which is more specifically referred to as chemical fog.

Chemical fog, apparent in most silver halide systems, has been reduced by prior art methods of processing exposed silver halide material in the presence of compounds which restrict development of unexposed silver halide. Such compounds can be incorporated in the silver halide emulsion or in the processing solutions for developing such silver halide emulsions. Compounds which have been found to have a chemical fog inhibiting effect on emulsions which have been subjected to high temperature and high humidity conditions are referred to as emulsion stabilizers. On the other hand, compounds which have been found to have chemical fog inhibiting effects on emulsions which have not been exposed to adverse storage conditions are referred to as antifoggants. Although a large number of emulsion stabilizers and antifoggants have been used in the prior art, many of these compounds cause undesirable losses in emulsion speed and contrast and others lack adequate compatibility with emulsion gelatin. While certain organic and inorganic bromides have in the past been used as antifoggants, chlorides have generally shown little or no activity.

SUMMARY OF THE INVENTION According to this invention, there is incorporated into the silver halide emulsion of a photographic element or in a layer contiguous to the silver halide emulsion, a fogstabilizing amount of an amide containing the group =PX or wherein X is chloro or bromo, said group being attached to an amidic nitrogen atom. These compounds stabilize the emulsion against fog when the dried emulsion has been subjected to a prolonged high humidity and temperature incubation period without adversely affecting other sensitometric properties such as speed and contrast.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fog stabilizing compounds of this invention are preferably selected from the group consisting of those having the formulas wherein n is 1 or 2; each A is carbonyl or sulfonyl; each R is an aliphatic or aromatic radical which may be substituted with other groups such as halo, nitro, alkoxy, etc. and is monovalent when n is l and is divalent when n is 2; R is hydrogen or lower alkyl; and each X is chloro or bromo. When n is 1, the R groups may be, for example, alkyl, halogenated alkyl, alkoxy, aryl, aralkyl, aralkoxy, etc. When n is 2, the R groups may be, for example, phenylene or alkylene. When R is a lower alkyl group, it preferably contains from 1 to 6 carbon atoms.

The fog stabilizing compounds of this invention may be incorporated into the silver halide emulsion of a photographic element or in a layer contiguous to the silver halide emulsion in a fog stabilizing amount. They may be used in any amount which will stabilize the silver halide emulsion against fog. In general, a concentration of the compound in an amount of about 0.01 to about 20, preferably about 0.03 to about 15, grams per mole of silver in the silver halide emulsion is useful.

The silver halides employed in the photographic emulsions include any of the photographic silver halides, as exemplified by silver bromide, silver iodide, silver chloride or mixed silver halides such as silver chlorobromide, silver bromoiodide and the like. The silver halides used can be those which form latent images predominantly on the surface of the silver halide grains or those which form latent images inside the silver halide crystals such as described in US. Patent 2,592,250 of Davey and Knott issued Apr. 8, 1952.

Photographic emulsions containing the antifogging and stabilizing agents of the present invention may be sensitized using any of the well-known techniques in emulsion making, for example, by digesting with naturally active gelatin or various sulfur compounds and/or gold compounds. The emulsions may be sensitized with salts of noble metals of Group VIII of the Periodic Table which have an atomic weight greater than The emulsions can also be sensitized with labile selenium and noble metals as disclosed in US. Patent 3,297,446 of Dunn issued Jan. 10, 1967. The emulsions may also contain speed-increasing addenda such as quaternary ammonium salts, polyethylene glycols, or thioether sensitizers.

The emulsions of the invention may also contain conventional additives such as gelatin plasticizers, hardeners and coating aids. These emulsions may be used in X-ray and other non-optically sensitized emulsions, and may also be used in orthochromatic, panchromatic and infrared sensitive emulsions. The additives may be added to the emulsion before or after sensitizing dyes, if any, are used.

The emulsions may be used in photographic elements intended for color photography, and thus may contain color-forming couplers, or used as emulsions to be developed by solutions containing couplers or other colorgenerating materials, or emulsions of the mixed-packet type, as disclosed in US. Patent 2,698,794 of Godowsky issued Jan. 4, 1955, or emulsions of the mixed-grain type, such as disclosed in US. Patent 2,592,243 of Carroll and Hanson issued Apr. 8, 1952.

The emulsions obtained in accordance with this invention may be used in diffusion transfer processes which utilize the undeveloped silver halide in non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a silver layer in close proximity to the original silver halide emulsion layer. Such processes are described in US. Patents 2,352,014 of Rott issued June 20, 1944; 2,543,181 of Land issued Feb. 27, 1951; and 3,020,155 of Yackel et al. issued Feb. 6, 1962. The emulsions may also be used in diffusion transfer color processes which utilize a diffusion transfer of an imagewise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another.

A wide variety of emulsion vehicles and dispersing agents for silver halide grains may be employed singly or in combination with each other, for example, gelatin, colloidal alubumen, cellulose derivatives and synthetic resins, such as polyvinyl compounds. Examples of typical colloids which may be used are poly(vinyl alcohol), hydrolyzed poly(vinyl acetate), hydrolyzed cellulose ester, Water-soluble ethanolamine cellulose acetate, polyacrylamide, copolymers having a combined acrylamide content of 3-60 percent, copolymers of alkyl acrylate and acrylic acid, a vinyl alcohol copolymer containing urethane carboxylic acid groups or containing cyano-acetyl groups, or polymeric material which results from polymerizing a protein or saturated acrylated protein with a monomer having a vinyl group such as disclosed in US. Patent 2,852,382 of Jones issued Sept. 16, 1958. Such polymeric additives may be employed as latices or hydrosols in the preparation of the photographic emulsions of our invention.

The photographic emulsions can be coated on a wide variety of supports, preferably supports which are transparent and/or flexible. Typical supports include metals such as aluminum, paper, cellulose acetate film, polyvinyl acetate film, polystyrene film, polypropylene film and other polyolefin film, polycarbonate film, polyethylene terephthalate or other polyester film and other related materials. Supports such as paper which are partially acetylated or coated with an a-olefin polymer, particularly a polymer of an a-olefin containing 2-10 carbon atoms, as exemplified by polyethylene, polypropylene, ethylenebutene copolymers and the like, give good results.

The invention can be further illustrated by the following examples or preferred embodiments thereof; although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention.

The fog inhibiting agents used in the practice of this invention are prepared by techniques known in the art and their preparation is exemplified in Examples 1 to 6.

EXAMPLE 1 Trichlorophosphazosulfonylmethane, M.P. 50-52 C. (lit. 47-50 C.), is prepared by the method of A. V. Kirsanov and N. L. Egorova, J. Gen. Chem. (U.S.S.R.) 25, 171 (1955) trans. ed. The compound has the formula CH3SOZN=PCI3.

The cited reference teaches the synthesis of trichlorophosphazosulfonalkyls by the reaction of phosphorous pentachloride with the corresponding alkylsulfonic acid amides. Accordingly, 0.02-0.03 mole of pulverized pure, dry amide of methylsulfonic acid is placed in a 50 ml. flask closed with an air condenser protected by a calcium chloride tube with a 5% molecular excess of pure, pulverized phosphorous pentachloride and heated. After completion of the reaction, the excess phosphorous pentachloride is quantitatively distilled off and precipitated in the condenser. Trichlorophosphazosulfonylmethane remains in the flask as a colorless liquid which soon crystallizes.

EXAMPLE 2 Trichlorophosphazocarbonyltrichloromethane, M.P. 77.5-79.5 C. (lit. 7779 C.), is prepared by the method of A. V. Kirsanov and G. I. Derkach, J. Gen. Chem.

4 (U.S.S.R.) 26, 2239 (1956) trans. ed. The product has the formula Cl CCON=PCl The cited reference teaches the synthesis of trichlorophosphazotrichloroacetyl by the reaction of trichloroacetamide with phosphorous pentacloride. Accordingly, a mixture of 0.5 mole trichloroacetamide, ml. carbon tetrachloride, and 0.515 mole pulverized phosphorous pentachloride is heated at 70-75 C. until no more hydrogen chloride is evolved. The solvent is then driven off in vacuum, leaving a residue of crude trichlorophosphazotrichloroacetyl (i.e. trichlorophosphazocarbonyltrichloromethane), which sets to a solid crystalline mass on cooling. The product is recrystallized from 160 ml. of ligroine to yield pure substance in the form of stout, colorless, transparent prisms.

EXAMPLE 3 A stirred mixture of 20.0 grams of m-carbamoylbenzenesulfonamide and 42.5 grams of phosphorus pentachloride in 250 ml. of dry benzene is heated slowly to reflux while the system is being swept by dry nitrogen. When hydrogen chloride evolution has ceased (three hours) the reaction mixture is filtered and the solvent removed at reduced pressure to give 47.0 grams of pale yellow-orange product, M.P. 67-68 C. The product, 1- tricholorphosphazosulfonyl 3 trichlorophosphazocarbonylbenzene, has the formula SlOzN=P 013 Result of analysis.Calcd (percent): C, 17.9; H, 0.9; Cl, 45.2; N, 5.9. Found (percent): C, 19.1; H, 0.9; Cl, 44.1; N, 5.7.

EXAMPLE 4 N-(methanesulfonyl)phosphoramidie dichloride, M.P. 102103 C., is prepared by the method of E. S. Lerchenko, I. E. Scheinkman and A. V. Kirsanov, J. Gen. Chem. (U.S.S.R.) 33, 3244 (1963) trans, ed. The product has the formula CH SO NHPOCl Results of analysis.Calcd (percent): C, 5.7; H, 1.9; Cl, 33.5; N, 6.6. Found (percent): C, 6.2; H, 2.0; CI, 32.6; N, 6.6.

As indicated by the cited reference, N-(methanesulfonyl)-phosporamidic dichloride is obtained by the reaction of 0.2 mole of trichlorophosphazosulfonylmethane, in 50 ml. of benzene, with 0.2 mole of anhydrous formic acid. After completion of the reaction, the crystalline precipitate is separated by suction filtration, washed with a small quantity of benzene, and dried in vacuo.

EXAMPLE 5 Benzolyphosphoramidic dichloride having a meelting point of 104-104.5 C. when a sample is inserted at 90 C. is prepared by the method described by A. V. Kirsanov and R. G. Makirta, J. Gen. Chem. (U.S.S.R.) 26, 1029 (1956) trans. ed. The product has the formula C H CONHPOCI This amide is prepared by the formolysis of trichlorophosphazobenzoyl in benzene solution. To a solution of 0.01 mole trichlorophosphazobenzoyl in 10-15 m1. dry benzene, is slowly added 0.01 mole of anhydrous formic acid. A vigorous exothermic reaction commences immediately, with evolution of carbon monoxide and hydrogen chloride. Upon cessation of evolution of the gases, and cooling, the acid dichloride precipitates, and may be separated and washed with benzene.

EXAMPLE 6 N (benzyloxycarbonyl)phosphoramidic dichloride M.P. 86-87 C. (lit. -86 C.) is prepared by the method of A. V. Kirsanov and M. S. Marenets, J. Gen. Chem. (U.S.S.R.) 31, 1496 (1961) trans. ed. The product has the formula C H CH OCONHPOCl The cited reference teaches the preparation of dichlorides of urethan-N-phosphoric acids such as N-(benzyloxycarbonyl)phosphoramidic dichloride, using phosphorous pentachloride and dichloroethane as the starting materials. Ten gram moles of phosphorous pentachloride and 600 ml. of dichloroethane are placed in a five-liter reaction vessel equipped with a stirrer, a heated dropping funnel, a reflux condenser and a thermometer (with the bulb in the reaction mixture). The oil bath on which it is placed is heated to 100105 C. and when the temperature of the reaction mixture reaches 70-80 C., g. moles of ethylurethan, melted and heated to 7080 C., are poured in at a rate such that the temperature of the reaction mixture is maintained within the limits of 70 80 C. This requires about an hour at a bath temperature of 100-105 C. The completion of the reaction can be deetermined by the disappearance of the last pieces of phosphorous pentachloride, by the cessation of gas formation, and by an increase in the temperature of the reaction mixture (while the temperature of the oil bath remains constant). The gases that are given off during the reaction are passed through a trap containing dichloroethane in order to absorb the dichloride of isocyanatophosporic acid carried along by a current of hydrogen chloride and methyl or ethyl chloride. On completion of the reaction, the contents of the trap are combined with the reaction mixture and distilled in vacuo through a small column to obtain dichloride of isocyanatophosphoric acid. To a solution of the dichloride of isocyanatophosphoric acid in petroleum ether, while cooled (0+5 C.) and stirred, is added an equivalent quantity of phenol. The dichlorides of urethan-N-phosphoric acids precipitate in crystalline form. They are filtered oil, washed with petroleum ether and dried in a vacuum over paraflin.

Each of the compounds prepared in Examples 1 to 6 are added to separate portions of a high speed silver bromoiodide emulsion which has been panchromatically sensitized with a cyanine dye. Each emulsion sample is coated on a cellulose acetate film support at a coverage of 459 mg. of silver and 1040 mg. of gelatin per square foot. A sample of each film coating is exposed on an intensity scale sensitometer, processed for five minutes in Kodak Developer DK50, fixed, washed and dried. The photographic results obtained from these tests are listed in the following table:

be effected without departing from the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A composition comprising a photographic silver halide emulsion containing a fog stabilizing amount of an amide having the formula wherein n is 1 or 2; each A is carbonyl or sulfonyl; R is an aliphatic or aromatic radical and is mono'valent when n is 1 and is divalent when n is 2; R is hydrogen or lower alkyl; and X is chloro or bromo.

2. The composition of claim 1 wherein said amide is present in an amount of about 0.01 gram to about 20 grams per mole of silver in said silver halide emulsion.

3. The composition of claim 2 wherein said amide is trichlorophosphazosulfonylmethane.

4. The composition of claim 2 wherein said amide is trichlorophosphazocarbonyltrichloromethane.

5. The composition of claim 2 wherein said amide is 1-trichlorophosphazosulfonyl 3 trichlorophosphazocarbonylbenzene.

6. The composition of claim 2 wherein said amide is N-(methanesulfonyl)phosphoramidic dichloride.

7. The composition of claim 2 wherein said amide is benzoylphosphoramidic dichloride.

8. The composition of claim 2 wherein said amide is N-(benzyloxycarbonyl)phosphoramidic dichloride.

9. A composition comprising a photographic silver halide emulsion containing a fog stabilizing amount of an amide having the formula wherein n is 1 or 2; each A is carbonyl or sulfonyl; R is an aliphatic or aromatic radical and is monovalent when n is 1 and is divalent when n is 2; R is hydrogen or lower alkyl; and X is chloro or bromo.

10. The photographic element of claim 9 wherein said amide is present in an amount of about 0.01 gram to about 20 grams per mole of silver in said silver halide emulsion.

TABLE 2 week incubation at 120 F. Fresh and relative humidity Compound pre- Cone. of pared in Compound Rel. Rel. example in g./m0le Ag speed Gamma Fog speed Gamma Fog Control 100 1. 34 0. 18 45 0.88 0. 75 1 87 1. 47 0. 12 74 1. 27 0. 17 100 1. 37 0. 14 80 1. 15 0. 31 83 1. 20 0.11 76 1.15 0.15 100 1. 26 O. 18 67 0. 97 0. 51 97 1. 32 0.10 94 1. 20 0.15 91 1. 37 0. 09 100 1. 27 0. 11 100 1. 52 0. 17 33 0. 84 0. 77 95 1.65 0.11 73 1. 22 0.11

The results in the above table show that the compounds of this invention stabilize the emulsion against fog when the dried emulsion has been subjected to a prolonged high humidity and temperature incubation period without adversely affecting other sensitometric properties such as speed and contrast, i.e., there is little or no additional speed loss upon incubation in contrast to the controls and the emulsion is stabilized against large losses in gamma.

Although the invention has been described in considerable detail with reference to certain embodiments thereof,

11. The photographic element of claim 9 wherein said amide is trichlorophosphazosulfonylmethane.

12. The photographic element of claim 9 wherein said amide is trichlorophosphazocarbonyltrichloromethane.

13. The photographic element of claim 9 wherein said amide is 1 trichlorophosphazosulfonyl-3-trichlorophosphazocarbonylbenzene.

14. The photographic element of claim 9 wherein said amide is N-(methanesulfonyl)phosphoramidic dichloride. 15. The photographic element of claim 9 wherein said it will be understood that variations and modifications can amide is benzoylphosphoramidic dichloride.

16. The photographic element of claim 9 wherein said amide is N-(benzyloxycarbonyl)phosphoramidic dichloride.

17. The photographic element of claim 9 wherein said amide is present in said silver halide emulsion.

18. The photographic element of claim 9 wherein said amide is present in a layer contiguous to said silver halide emulsion.

References Cited UNITED STATES PATENTS 3/1964 Jeffreys 96-109 4/1966 Dersch et a1. 96109 

